(1) Field of the Invention
My invention is in the field of commercial logging operations and involves portable power-driven chain saws which are used to cut trees and logs. More particularly, my invention is in the field of attachments for power chain saws. The invention is used for debarking trees and logs and for cutting or shaping logs.
It is often necessary to use a power chain saw to cut trees and logs which are covered with abrasive materials, such as mud, dirt, or volcanic ash. For example, in the area around the volcano Mount St. Helens the trees and logs are all covered with ash from the recent volcanic eruption. When cutting such trees with a power chain saw, the abrasive materials covering the outside of the trees will act to dull and wear out the saw chain, will get into the chain groove, and will cause the saw bar to wear out much more quickly than under normal tree cutting conditions. In general, these abrasive materials greatly increase the normal cost of operating a power chain saw.
One solution to this problem is to use an ax to chop off the tree bark and foreign matter, but this is a slow process which also increases the cost.
(2) Description of the Prior Art
The prior art includes U.S. Pat. No. 2,708,468 to Lantz for a chain-drum rossing device which includes two curved rasp-type drums which are rotated by an idler sprocket wheel driven by the saw chain. Lantz also broadly mentions the concept of shields of a semi-cylindrical shape attachable as a housing over the rasping drums for protection to the operator from flying particles and shavings.
U.S. Pat. No. 2,821,216 to West et al discloses a portable chain saw attachment for clearing fire lanes. In its primary form, the West et al attachment comprises four flails arranged on a shaft at the sides of a chain driven sprocket. West et al also discloses the use of a spiral cutting blade on a drum for cutting a trench.
And U.S. Pat. No. 2,889,860 to Bagley teaches a debarking adapter for a chain saw having a rotating cutter mounted thereon. The cutter consists of a block mounting four cutter blades.